You only fill those out if you buy from a licensed federal dealer though. Private sales are still legal in most states. I'm sure these guys will think of something to keep their guns. And I don't know any of them that will put up with being detained over it. They'll fight back. No one I know, and I mean no one, will willingly hand over their guns. The quotes I see are "bullets first," "come and get them," "molon labe," "from my cold dead hands," etc. If they plan to go door to door, its gonna get bloody from what I can tell.